Sexology as a field is both science and social science — it encompasses rigorous biological studies of reproduction and sexual response, as well as psychology, sociology, and history. It wasn't until the nineteenth century, however, that scientists started referring to themselves as "sexologists." From that time forward, there has been a rich and diverse scientific literature devoted to sex. Here are eleven works of sexology that changed history, blew people's minds, or are just plain fascinating.

1. Psychopathia Sexualis, by Richard von Krafft-Ebing
Published in 1886, this book was the German psychiatrist Krafft-Ebing's attempt to categorize every form of "deviant" sexuality he ran across in his medical practice. It's written as a series of case studies, with ample quotes from the doctor's patients describing everything from rubber fetishism and incest, to what today we'd call BDSM and homosexuality. This book helped define the field of sexology, and ironically made it possible for so-called deviants (like homosexuals) to find more acceptance in the following decades.

2. Memoirs of a Sexologist, by Ludwig Lenz
Published in the mid-1940s, Lenz' book is a fascinating memoir of his work in the early twentieth century as a sexologist, treating everyone from transsexuals who wanted sex changes, to prostitutes who followed soldiers' camps during World War I. His descriptions of early sexual medicine are hair-raising (briefly, there was a fad for implanting rabbit testicles in human men for "vigor"), but his descriptions of his patients are compassionate. Unlike Krafft-Ebing, Lenz never condemns the "deviants," but instead tries to help them stay healthy and find their way in a world where gay marriage and fetish fashions were just a futurist dream.

3. Sexual Behavior in the Human Male, by Alfred Kinsey
Kinsey began his career as an entomologist who studied and categorized wasp species, and when he decided abruptly to turn his eye to sexuality he brought his phylogenist's sensibility with him. Like Krafft-Ebing, he wanted to categorize human sexual behavior — except he pledged to study and chronicle all of it, socially acceptable or not, without judgment. The result was this massive tome in the 1940s, based on hundreds of anonymous interviews with men. The book was an insane smash hit, and helped popularize the idea that "1 in 10 men" had homosexual experiences (this was probably selection bias, since Kinsey interviewed a disproportionate number of men in New York's gay bars). But it also revealed to the world how common oral sex was, as well as pre-marital sex.

4. Human Sexual Response, William Masters and Virginia Johnson
Published in the late 1960s, this book explored the physiological aspects of sex, and popularized the idea of the "sexual response cycle." The researchers had put countless volunteers into a machine that measured heart rate, galvanic skin response, and muscle contractions while the people masturbated to orgasm. As a result, Masters and Johnson were able to characterize the four stages of arousal and orgasm, which are excitement, plateau, orgasm, and resolution, each of which has characteristic physiological symptoms, from a flushed chest in plateau to involuntary muscle contractions every .8 seconds during orgasm. Strangely, this book is out of print.

5. My Secret Garden, by Nancy Friday
Friday published this work in the early 1980s, the result of hundreds of interviews with women about their sexual fantasies — which appear basically unedited in this book. Half-erotica, half-sexology, the book was a celebration of the female sexual imagination and would have made Krafft-Ebing blush. It also helped raise mainstream awareness of the fact that sexual fantasies are normal, and that just because you fantasize about something doesn't mean you want to do it.

6. The Mating Mind, by Geoffrey Miller
In the late twentieth century, some of the most interesting works of sexology are more properly understood as evolutionary psychology. In this book, evolutionary psychologist Miller explores the idea that sexual selection among humans was driven by our ancestors' desire for people who were smart and innovative. In other words, humans got smarter by choosing to mate with people who were smart. Not only is it a provocative and entertaining thesis, but it's basically a theory of evolution that posits geeks as a natural outcome.

7. The Ethical Slut, by Dossie Easton and Janet Hardy
Published in the 1990s, this underground bestseller by therapist Easton and writer Hardy offered readers helpful psychological advice for having healthy, trusting romantic and sexual relationships with more than one person at a time. It helped to popularize the term "polyamory" for multi-partner relationships, and overturned decades of misconceptions about non-monogamy by showing that not all of these relationships were destructive "cheating" arrangements — instead, they could be just as healthy as monogamous ones, and certainly more honest.

8. The Myth of Monogamy, by David Barash and Judith Lipton
In this book, psychologist Barash and biologist Lipton offer another perspective on the issues in The Ethical Slut, by exploring how many animals that scientists dubbed "monogamous" are anything but. They develop the idea that there is a difference between social monogamy (lifetime partnerships) and sexual monogamy (sexual exclusivity) and use genetic testing to reveal that many animals are socially monogamous and almost none are sexually monogamous. Including humans.

9. The Science of Orgasm, by Barry Komisaruk, Carlos Beyer-Flores, and Beverly Whipple
Like Masters and Johnson, Komisaruk and his colleagues wanted to learn more about the biological processes underlying orgasm. So they found a unique group of subjects who could have orgasms inside fMRI imaging machines, and discovered what orgasm does to the brain. This could go a long way toward helping women who have difficulty with orgasm, and might one day result in a female version of viagra.

10. Evolution's Rainbow, by Joan Roughgarden
Evolutionary biologist Roughgarden was one of the first scientists to bring together several studies on sexual diversity in nature — from fish that change their sex, to hermaphrodites and homosexual animals — and explain why this kind of diversity might have evolved. She suggests that sexual diversity is completely natural, and that homosexuality and transsexuality in humans is far from Krafft-Ebing's idea of "deviant." Indeed, it is part of what makes us and many other species successful.

11. Sex at Dawn, by Christopher Ryan and Cacilda Jetha
Ryan and Jetha offer an alternate view on the early history of human culture, describing how multiple partner relationships and matriarchy are as crucial to humans' early psychological development as patriarchy and monogamy are. In the process, they carry on the project of many contemporary sexologists from Easton and Hardy to Roughgarden, which is to establish that what we think of as "natural" sexual relationships today are anything but. From its earliest beginnings, human sexuality was a lot more complicated and fluid than the standard heterosexual, male-breadwinner marriage would suggest.